2010 USGS ARRA Michigan TriCounty Lidar

TASK NAME: Michigan Tri-County LiDAR (ARRA Lidar Task Order)

LiDAR Data Acquisition and Processing Production Task

USGS CONTRACT: G10PC00057

TASK ORDER NUMBER: G10PD00844

CONTRACTOR: Woolpert, Inc.

LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS positioning, and inertial measurment technologies.The LiDAR systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. This data was collected at a resolution of one and one half point point per square meter. The final products include first, last, and at least one intermediate return LAS, a bare earth model, and intensity data in separate files.

This task order consisted of LiDAR data acquisition and processing for Clinton, Eaton and Ingham Counties in southeastern Michigan. The task order area of interest encompasses approximately 1,810 square miles. The task required the LiDAR data to be collected at a minimum of one and one half (1.5) point per square meter (1.5 meter GSD). The LiDAR data was collected to meet a vertical accuracy requirement of 15.0 cm (0.49 ft) RMSE, or better, so that when combined with breaklines, the data adequately supports the generation of two (2) foot FEMA compliant contours. The final LiDAR data was delivered as 5,000' x 5,000' tiles, aligned to even 5,000' coordinates.

USGS CONTRACT: G10PC00057

TASK ORDER NUMBER: G10PD00844

CONTRACTOR: Woolpert Inc.

The reflective surface data represents the DEM created by the laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface, to be reflected by a subsequent surface as represented by the last return data. Intensity information is captured from the reflective surface pulse and indicates the relative energy returned to the sensor, as compared to the energy transmitted. The intensity image is not calibrated or normalized but indicates differences in energy absorption due to the the interaction of the surface materials with laser energy, at the wavelength transmitted by the sensor. The bare earth model is created by identifying the returns that fall on the ground surface and by interpolating a surface between these points. In this manner, buildings and vegetation are removed from the bare earth model. This data set does not include bridges and overpasses in the bare earth model as the delineation point for these structures is not reliably discernable in the LiDAR data.

Translation of files to formats other than those described here is the sole responsibility of individuals downloading the data. Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners

Data is available online for bulk or custom downloads

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.1850

Horizontal accuracy is +/- 3.8-foot at the 95% confidence level using RMSE(r) x 1.9600 as defined by the FGDC Geospatial Positional Accuracy Standards, Part 3: NSSDA. Quantitative value: 3.8, Test that produced the valued: LiDAR system calibration is available in the project report.

The LiDAR data vertical accuracy RMSE is 0.28 ft.

The data collected under this Task Order meets the National Standard for Spatial Database Accuracy (NSSDA) accuracy standards. The NSSDA standards specify that vertical accuracy be reported at the 95 percent confidence level for data tested by an independent source of higher accuracy. (http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part3/index_html).

The Fundamental Vertical Accuracy (FVA) of the TIN: 8.65 cm (0.28 ft) at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 18.5 cm in the "open terrain" land cover category. This data set tested to 0.28 ft.

The Consolidated Vertical Accuracy (CVA): 31.5 cm (1.03 ft) at a 95% confidence level, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data, i.e., based on the 95th percentile error in all land cover categories combined. This data set tested to 0.53 ft. for all categoires.

Quantitative value: 0.28, Test that produced the value: Tested 0.28 feet vertical accuracy at 95 percent confidence level.

The LIDAR data is visually inspected for completeness to ensure that are no gaps between flight lines.

All formatted data are validated using commercial GIS software to ensure proper formatting and loading prior to delivery.

Data is backed up to tape and to cloud storage.